Insulate Garage Ceiling With Foam Board and How to Do It Properly

Many homeowners want to insulate garage ceiling with foam board, believing that it will protect the area from moisture or seepage. When you insulate your garage, you want to make sure that the interior isn’t exposed to cold air while maintaining the already warm air inside for a longer time at the same time.

Whereas most people think that foam board insulation is one of the best options, there are actually other insulation types out there.

How to Install Foam Board Insulation Ceiling

The foam board insulation is perfect for insulating an already existing construction. This insulation type is ideal for upgrading the (garage) ceiling when the interior’s portion is already built up.

insulate garage ceiling with foam board

You can attach the foam board through insulation addition (as well as the air seal) with these steps:

  • Install the (rigid) foam sheathing insulation on the existing garage ceiling’s underside. This kind of construction usually has its own finished surface (of plaster and lath or gypsum board), where you can ‘attach’ the board. Another possible way is to attach the foam board on the ceiling joists’ underside, but this method is only applicable when your garage has its own unfinished ceiling with the joist cavities being exposed.
  • When the joists cavities are completely exposed, the insulating sheathing layer would be detailed (to serve) because of the foam’s air control layer with the taped (or caulked) edges and taped seams.
  • You can install blocking if you want to re-install the existing attachments or services on your ceiling.

Read also: 4 Recommendations of Best Adhesive for Foam Board to Concrete

In the most detailed steps, you should understand the ‘anatomy’ of the foam board. It has a foil side, named radiant barrier, whose function is to keep the building or area warm. When properly used, it can help eliminate heat load coming into the building from the outside, especially from the roof deck or walls.

If you want the radiant work to function fully, you need to ensure an air gap between the roof deck (or wall) and the foil.

  • If you press that foil side against your wall (the foil facing outward), the radiant work won’t work but the insulation will. You reduce the conductive heat entering the building, but not so much with the radiative heat load.
  • If you use something to create the gap (between the insulation board and wall) with the foil face out, you have your own radiant barrier. In this manner, both your insulation and radiant barrier work perfectly.
  • If you install the foam board with the foil going inward, you basically keep the warmth within the building.

Cost to Insulate Garage Ceiling

The location where you want to install the insulation will determine the cost. The more complicated the job is, the more money should be expected. Let’s say that you want to insulate the garage doors. You ‘only’ need to pay from $500 to $700. If you want to insulate the floor, expect to spend between $600 and $900.

When you want to insulate the ceiling, expect to spend between $260 and $3,000. The walls are the costliest one, ranging from $790 to around $9,000.

Insulate Garage Ceiling With Foam Board of Different Types

Besides the foam board type, there are other ceiling insulation types, including:

  • Fiberglass, is quite popular and common. It’s easy and inexpensive, but it’s moisture sensitive
  • Cellulose, which is perfect for holes and cavities. It’s fire-resistant and eco-friendly, but it’s costly and it needs drywall
  • Spray foam, which is energy efficient and high-end. It’s mold and insect resistant as well as airtight, but it’s expensive and you need professional help.

Make sure that you pick the right one before you install everything. It’s best if you can consult a professional service before starting the project.

Gravatar Image
Insulator is a skilled author and Insulation expert with years of experience in the field. He has authored several articles and books on various aspects of insulation installation, maintenance, and repair.